Community Forums

Dennis S · 08-21-2012, 08:17 PM

Hi everyone,
I have twin 24 series batterys charged by solar. Currently my charging circuit charges battery #1 and via 2 interconnect cables, battery #2 gets it's charge. I use 2 guage cable for the batteries, my charge conntroller puts out 11 amps, so that part is fine.

I was thinking of hooking the "+" cable from the charge controller to battery #1 and hooking the "-" cable to battery #2. I'm thinking it will force the charge across both batteries rather than just one battery.

Any actual experience with this? All comments are welcome.

Thanks,
Dennis

IWillRVToo · 08-22-2012, 03:21 PM

Hi, Dennis. I read your post and then I did some reading myself.

"I was thinking of hooking the "+" cable from the charge controller to battery #1 and hooking the "-" cable to battery #2. I'm thinking it will force the charge across both batteries rather than just one battery."

That^ appears to be the proper or best or most common way to do it.
The alternative is to split the batteries and charge them separately.

DonDee · 08-22-2012, 03:39 PM

I don't see how you're changing anything??
You have 2 batteries in parallel either way.

With 2 batteries in parallel, the charging entity will 'see' only the highest volt battery and react to that, tapering the charge rate, leaving the other battery to get what it can via trickle from the high battery. Better than no charge but not ideal.

IWillRVToo · 08-22-2012, 04:03 PM

"I read your post and then I did some reading myself."

"That^ appears to be the proper or best or most common way to do it."

I don't know batteries well enough to say if it is good or bad or right or wrong.
Spend about an hour reading about it like I did.
What is this ideal that you speak of?

wardy · 08-22-2012, 04:46 PM

Dennis,

You are planning to do the best method for two batteries in parallel. BTW, since they are in parallel they will read the exact same voltage across their respective terminals. If they were in series you would see a difference but ONLY in series not in parallel.

Shadowcatche · 08-29-2012, 06:25 PM

Two batteries either in parallel or series must be the same age and capacity or the weaker battery will drag down the stronger. There is no advantage in an RV of using two 6V in series vs similar capacity 12v batteries.
Monitoring the state of charge and the performance of your solar output and current load is the key to making sure that your batteries reach full charge with regularity.
One of the best sources for info Deep Cycle Battery FAQ

Dennis S · 08-29-2012, 09:50 PM

Thanks for your input.
This weekend I found a weak cell and thus, never a full charge. Both batterys are 4 years old and getting tired. I think this winter I'll make a battery carrier to allow me to upgrade to two 27 series batteys. The main reason to go to the 27s is because should one of my truck batterys go bad I can swap it out and get to town for a replacement (we camp in the desert a lot rock hounding). Once I get everything built I'll post what I did incase some one else wants ideas.

Thanks, Dennis